WAEC Mathematics Past Questions & Answers - Page 66

326.

In the diagram MN is a chord of a circle KMN centre O and radius 10cm. If < MON = 140o, find, correct to the nearest cm, the length of the chord MN.

A.

19cm

B.

18cm

C.

17cm

D.

12cm

Correct answer is A

From the diagram

sin 70o = \(\frac{x}{10}\)

x = 10sin 70o

= 9.3969

Hence, length of chord MN = 2x

= 2 x 9.3969

= 18.7938

= 19cm (nearest cm)

327.

Halima is n years old. Her brother's age is 5 years more than half of her age. How old is her brother?

A.

\(\frac{n}{2} + \frac{5}{2}\)

B.

\(\frac{n}{2}\) - 5

C.

5 - \(\frac{n}{2}\)

D.

\(\frac{n}{2}\) + 5

Correct answer is D

Halima's age = n years old

Her brother's age = \(\frac{n}{2}\) + 5

328.

The ratio of the exterior angle to the interior angle of a regular polygon is 1:11. How many sides has the polygon?

A.

30

B.

24

C.

18

D.

12

Correct answer is B

Let a represent an interior angle; e represent an exterior angle. A section of the polygon is down in the diagram.

\(\frac{e}{a}\) = \(\frac{l}{11}\) given

a = 11e

a + e = 180o(angles on a straight line)

11e + e = 180o

12e = 180o

e = \(\frac{180^o}{12}\)

= 15o

Hence, number of sides

= \(\frac{360^o}{\tect{size of one exterior angle}\)

= \(\frac{360^o}{14^o}\)

= 24

329.

Find the lower quartile of the distribution illustrated by the cumulative frequency curve

A.

17.5

B.

19.0

C.

27.5

D.

28.0

Correct answer is B

Lower quartile,

Q1 = \(\frac{1}{4}\)Nth term

= \(\frac{1}{4}\) x 600th term

= 150th term

= 15.5 + 3 + 0.5

= 19

330.

Find the next three terms of the sequence; 0, 1, 1, 2, 3, 5, 8...

A.

13, 19, 23

B.

9, 11, 13

C.

11, 15, 19

D.

13, 21, 34

Correct answer is D

No explanation has been provided for this answer.